Apparatus for forming a film on a substrate

ABSTRACT

An apparatus for forming a film on a substrate includes a reaction chamber and gas supply lines. The gas supply lines supply gases for depositing and annealing the film. Depositing a dielectric film and annealing the dielectric film are performed in situ using the reaction chamber. Thus, the time required for forming the dielectric film is shortened, improving the productivity. Also, deposition and annealing of the dielectric film are performed in the same reaction chamber, so that less area is required for manufacturing equipment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to manufacturing of a semiconductordevice, and more particularly, forming of a thin film such as adielectric film in a capacitor.

2. Description of the Related Art

The capacitance (C) of a capacitor is proportional to the area (A) ofthe capacitor's electrodes and a dielectric constant (ε) of a dielectricmaterial between the electrodes, and inversely proportional to distance(d) between the electrodes, as shown in the following equation.

C αε(A/d)

Thus, increasing the area (A) of electrodes, using a dielectric filmhaving a high dielectric constant, or decreasing the distance betweenthe electrodes can increase the capacitance (C) of the capacitor.

As semiconductor devices become more highly integrated, the areasavailable for capacitor formation within semiconductor devices becomesmaller. Accordingly, techniques have been developed for increasing thecapacitance of capacitors formed in small areas. One technique usesthree-dimensional electrodes to increase the area (A) of the electrodes,but the three-dimensional electrodes are subject to structuralrestrictions. Use of a dielectric film having a high dielectric constant(ε) can increase the capacitance (C) of a capacitor and permit highsemiconductor integration. In addition, a thinner dielectric filmreduces the distance (d) between electrodes and produces highercapacitance of a capacitor, but reducing the distance (d) between theelectrodes often has the drawback of increasing the leakage current ofthe capacitor.

Recently, tantalum oxides, such as a tantalum pentoxide (Ta₂O₅) having ahigh dielectric constant (ε), have been tried as dielectric films forcapacitors. However, with a tantalum pentoxide film, leakage current canbe large when the film is thin. A problem with tantalum pentoxide isnon-uniform film deposition, and oxygen and carbon impurities oftenallow the leakage current through weak portions of the tantalumpentoxide film. To solve the leakage problem, several methods have beensuggested. Among the suggested methods is a dry-oxygen (dry-O₂)annealing, and a low temperature ultraviolet-ozone (UV-O₃) annealing at500° C. or less followed by a dry-oxygen annealing, IEEE Transactions onElectron Devices, Vol. 38, No. 3, March 1991, entitled “UV-O₃ andDry-O₂; Two-Step Annealed Chemical Vapor Deposited Ta₂O₅ Films forStorage Dielectrics of 64-MB DRAM's”, by Shinriki and Masayuki Nakata,which is hereby incorporated by reference in its entirety, discloses thelatter method. In the known methods, formation and UV-O₃ annealing ofthe tantalum oxide film are respectively performed in separate chambersshown in FIGS. 1 and 2.

Referring to FIG. 1, a chamber 8 for forming a tantalum oxide filmincludes a shower head 10 in an upper portion of chamber 8. Shower head10 receives pentaethoxytantalum as a source gas for the tantalum oxidefilm from a supply line 12 and oxygen (O₂) as a reaction gas from asecond gas supply line 14. A first valve 12 a and a second valve 14 aare in the first and second gas supply lines 12 and 14, respectively. Asusceptor 16 is on the floor of the chamber 8 for mounting of a wafer18. A pumping line 20 connects to the bottom of the chamber 8, and apump 22 attaches to the pumping line 20. After forming the tantalumoxide film, wafer 18 becomes a wafer 23, which is transferred to anannealing chamber 9 (FIG. 2). In annealing chamber 9, a UV-O₃ annealingis performed on the tantalum oxide film.

Referring to FIG. 2, UV-O annealing chamber 9 includes a quartz window11 on the ceiling thereof. A UV lamp housing 13 includes a UV lamp 15for generating UV rays that pass through quartz window 11 into chamber9. A shower head 17 below quartz window 11 is also made of quartz touniformly pass UV rays into chamber 9. Shower head 17 supplies a gasmixture containing oxygen (O₂) and ozone (O₃) gases that form an oxidefilm with a uniform thickness. Shower head 17 connects to an ozonizer 19installed outside chamber 9. A susceptor 21 is on the floor of chamber 9and below shower head 17, and wafer 23 having the tantalum oxide film ison susceptor 21. An ozone decomposer 25 connects to a bottom of chamber9 via a pumping line 27, and a pump 29 connects to ozone decomposer 25.

As described above, the conventional method forms a tantalum oxide filmand uses a separate chamber for a UV-annealing to remove defects fromthe tantalum oxide film.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, an apparatusfor forming a dielectric film on a semiconductor substrate includes ashower head on in a reaction chamber, and a mounting stand in thereaction chamber, below the shower head. The semiconductor substrate isloaded on the mounting stand. A first gas line for supplying a sourcegas for depositing the dielectric film and a second gas supply line forsupplying a reaction gas for depositing the dielectric film and anannealing gas, typically ozone, for annealing the dielectric filmconnect to the shower head.

When the dielectric film is a composite dielectric film, the first gassupply line may include several lines, which supply respective sourcegases for the layers of the composite dielectric film. An ozonizerconnects to the second gas supply line in parallel. The second gassupply line can include respective gas supply lines for supplying thereaction gas and the annealing gas.

A supply line for an inert gas such as nitrogen (N₂) or argon (Ar) gasmay connect to the second gas supply line for purging the reactionchamber and the second gas supply line. The inert gas supply line andthe second gas supply line can respectively include mass flowcontrollers (MFCs). An ozone decomposer connects to the reaction chambervia a pumping line between the ozone decomposer and the bottom of thereaction chamber. A pump connects to the ozone decomposer.

The apparatus may further include a second pumping line, which bypassesthe ozone decomposer, to protect the ozone decomposer from contaminationcaused by gas discharged during deposition of a dielectric film. Theozone decomposer connects to the ozonizer via an ozone purifying line,and a control valve on the pumping line directs the gas flow from thereaction chamber to the second pumping line or the ozone decomposer.

According to another embodiment of the present invention, a reactionchamber includes five (first through fifth) semiconductor substratemounting stands. Each of the second through fifth semiconductorsubstrate mounting stands faces respective shower heads. The chamberalso includes a gas spraying means capable of forming air curtains of aninert gas around the shower heads.

According to an aspect of the invention a method for forming adielectric film includes (a) depositing a dielectric film on asemiconductor substrate, (b) annealing the dielectric film at atemperature lower than a crystallization temperature of the film, and(c) annealing the dielectric film at a temperature higher than thecrystallization temperature. When a tantalum oxide dielectric film isformed, the tantalum oxide film is first annealed at approximately 450°C. in an ozone or oxygen atmosphere and then annealed in a dry-oxygen orwet-oxygen atmosphere.

The steps (a) and (b) or the steps (a), (b), and (c) can be performed insitu in an apparatus. In particular, a reaction chamber including ashower head for source and annealing gases and a susceptor for heatingthe semiconductor substrate can perform steps (a) and (b). A first gassupply line that supplies a source gas for forming the dielectric filmand a second gas supply line that supplies a reaction gas for formingthe dielectric film and an annealing gas connect to the shower head. Asecond dielectric film may be further formed on the dielectric film andthen annealed in situ in the same chamber. In the step (b), thesemiconductor substrate can be annealed by a resistance heating or alamp heating method. The source gas typically comprises a metal oxidegas corresponding to one selected from a group consisting of tantalumoxides such as pentaethoxytantalum (Ta(OC₂H₅)₅), titanium oxides andaluminum oxides. When a tantalum oxide gas is the source gas, oxygen(O₂) and ozone (O₃) gases are the reaction gas and the annealing gas,respectively. In the step (a), the first gas supply line supplies thesource gas, and the second gas supply line supplies the reaction gas.When there is a large difference in processing pressure between thesteps (a) and (b), a turbo molecular pump (TMP) reduces the timerequired for adjusting the pressure between steps (a) and (b).

Steps (a) and (b) can be performed in situ in the above-describedreaction chamber using five semiconductor substrate mounting stands. Onesuch process performs steps (a) and (b) while a semiconductor substrateremains on the same mounting stand. In this case, the steps (a) and (b)include the sub-steps of: pre-heating the semiconductor substrate havingthe thin film on the first semiconductor substrate mounting stand; andforming and annealing the dielectric films on the pre-heatedsemiconductor substrate.

Steps (a) and (b) can also be performed on different semiconductorsubstrate mounting stands. For example, the steps (a) and (b) includethe sub-steps of pre-heating a semiconductor substrate having the thinfilm on the first semiconductor substrate mounting stand, formingdielectric films on the semiconductor substrate while on the second andfourth stands, and annealing the dielectric films when substrates are onthe third and fifth semiconductor substrate mounting stands.

Steps (a), (b), and (c) can be performed in situ in a furnace or inrapid thermal processing (RTP) equipment.

For a tantalum oxide dielectric film, step (b) may be performed atbetween about 500 and about 700° C., preferably, 600° C., in an oxygenatmosphere, and step (c) may be performed at between about 700 and about900° C., preferably, 800° C., in an oxygen atmosphere.

According to another embodiment of the invention, a method for forming adielectric film includes (a) forming a dielectric film on asemiconductor substrate and (b) annealing the dielectric film. For thismethod, step (b) is performed at a temperature near the crystallizationtemperature of the dielectric film in an ozone atmosphere, and thedielectric film can be formed of tantalum oxide at between about 500 andabout 700° C., preferably, 600° C., in an ozone atmosphere.

According to still another embodiment of the invention, a method forforming a dielectric film includes (a) forming a dielectric film on asemiconductor substrate, (b) annealing the dielectric film at atemperature lower than the crystallization temperature of the film, and(c) second-annealing the dielectric film at a temperature higher thanthe crystallization temperature, wherein the steps (b) and (c) areperformed in situ in the same apparatus.

In the above embodiments, the material of the dielectric film isselected from the group consisting of tantalum oxide (Ta₂O₅), titaniumoxide (TiO₂), aluminum oxide (Al₂O₃), yttrium oxide, vanadium oxide andniobium oxide.

As described above, embodiments of the present invention share one gassupply for both forming and annealing of a thin dielectric film, andforming and annealing of the thin film are performed in situ in achamber having the shared gas supply. Accordingly, the present inventioncan reduce the processing time of the thin film, thereby improving theproductivity of a semiconductor device manufacturing process. Inaddition, inflow of impurities into the thin film is reduced, andequipment for forming and annealing of the thin film is simplified,reducing the amount of equipment required.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the present invention will become more apparent bydescribing in detail embodiments thereof with reference to the attacheddrawings in which:

FIG. 1 is a partial sectional view of a conventional reaction chamberfor forming a dielectric film;

FIG. 2 is a partial sectional view of a conventional chamber for UV-O₃annealing;

FIG. 3 is a graph showing change of a leakage current density aftertreatment of tantalum oxide films;

FIGS. 4 through 8 are flowcharts illustrating thin film formationmethods according to embodiments of the present invention;

FIGS. 9 and 10 are partial sectional views of reaction chambers forforming thin films according to embodiments of the present invention;

FIG. 11 is a partial plan view of a reaction chamber for forming a thinfilm according to another embodiment of the present invention; and

FIGS. 12 and 13 are graphs illustrating process recipes for thin filmformation methods according to embodiments of the present invention.

In the drawings, the thickness of layers and regions are exaggerated forclarity, and the same reference numerals in different drawings representthe same or similar elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described more fully with reference to theaccompanying drawings, which illustrate embodiments of the invention.This invention may, however, be embodied in many different forms andshould not be construed as being limited to the embodiments set forthherein; rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will convey the invention to thoseskilled in the art. It will also be understood that when a layer isreferred to as being “on” another layer or substrate, the former can bedirectly on the latter, or intervening layers may also be present.

Prior to describing an apparatus for forming a dielectric film and amethod for forming the dielectric film according to the presentinvention, the change in leakage current density of a dielectric film,e.g., a tantalum oxide (Ta₂O₅) film, according to the annealing method,is described.

Referring to FIG. 3, a tantalum oxide film was formed on a semiconductorsubstrate to a thickness of 90 Å. Leakage current densities of thetantalum oxide film were measured after four treatment methods.

In detail, first, the leakage current density of a tantalum oxide film(G1) which had only pretreatment without annealing was measured. Second,leakage current density of a tantalum oxide film (G2) which had beendry-annealed at 800° C. was measured. Third, leakage current density ofa tantalum oxide film (G3) which had dry-annealing at 800° C. afterUV-annealing at 450° C. was measured. Fourth, leakage current density ofa tantalum oxide film (G4) which has been dry-annealed at 800° C. afterannealing at 450° C. was measured. The results are shown in FIG. 3.

The tantalum oxide film with no annealing (G1) shows much higher leakagecurrent density than the annealed tantalum oxide films (G2, G3 and G4).The UV-O₃ annealing (G3) or O₃ annealing (G4) followed the dry-O₂annealing at 800° C. resulted in lower leakage current density than thedry-O₂ annealing at 800° C. (G2).

The almost identical results from G3 and G4 suggest that regardless ofwhether the initial annealing is UV-O₃ or O₃ annealing, when thetantalum oxide film is annealed again, the tantalum oxide film shows alow leakage current density. Thus, an apparatus for UV-ray productioncan be omitted in annealing the tantalum oxide film. In addition, areaction chamber capable of forming and annealing a thin film in situcan reduce the number of the thin film formation steps.

FIGS. 4 to 7 show methods for forming a dielectric film in accordancewith specific embodiments of the present invention.

Referring to FIG. 4, an initial step 70 deposits a dielectric film on,for example, a lower electrode of a capacitor, which is formed on asemiconductor substrate. The material of the dielectric film is selectedfrom a group consisting of a tantalum oxide (e.g., Ta₂O₅), a titaniumoxide (e.g., TiO₂), an aluminum oxide (e.g., Al₂O₃), an yttrium oxide, avanadium oxide and a niobium oxide. After step 70, a first annealing ofthe dielectric film is performed in step 72. Steps 70 and 72 areperformed in situ in the same reaction chamber in which the dielectricfilm was deposited. The first annealing is at a temperature lower thanthe crystallization temperature of the dielectric film. For example, ifthe dielectric film is the tantalum oxide film, the first annealing isperformed at between about 200° C. and about 700° C., preferably,approximately 450° C. The first annealing is in an ozone (O₃) or oxygen(O₂) environment. The in situ process of steps 70 and 72 can eliminatethe time required for opening/closing the reaction chamber in each stepand moving the substrate into another chamber. The in situ process alsoprevents contamination of the semiconductor substrate that may otherwiseoccur when the chambers are opened or the substrate is moved.

After the first annealing (step 72), a second annealing of thedielectric film is performed in step 74. The second annealing is at atemperature higher than the crystallization temperature of thedielectric film and in an O₂ environment. For example, if the dielectricfilm is formed of the tantalum oxide, the second annealing is performedat a temperature between about 700° C. and about 900° C., preferably,800° C., and the O₂ environment may contain a dry-O₂ or wet-O₂. Becausethe second annealing is at a temperature higher than steps 70 and 72, afurnace or rapid thermal processing (RTP) equipment is used for thesecond annealing.

A method for forming and annealing of a dielectric film illustrated inFIG. 5 is similar to the method of FIG. 4. The process conditions ofeach step are identical between the methods in FIGS. 4 and 5. However,in the method of FIG. 5, the depositing and first annealing of thedielectric film (steps 170 and 172) are repeated N times in situ beforethe second annealing (step 174). N is equal to or greater than 2. Inshort, the method of FIG. 5 repeats step 170 and step 172 to form thedielectric film. For example, in order to form a 100 Å thick dielectricfilm, step 170 forms a 25 Å thick dielectric film, and step 172 annealsthe film, and the steps 170 and 172 are repeated three times more. Thesecond annealing (step 174) is the same as step 74 of FIG. 4.

FIG. 6 illustrates another method for forming and annealing a dielectricfilm according to another embodiment of the present invention. Referringto FIG. 6, after forming the dielectric film (step 270), a firstannealing (step 272) and a second annealing (step 274) are performed insitu in an O₂ environment. Since the second annealing (step 274) isperformed at a temperature higher than the crystallization temperatureof the dielectric film as described with reference to FIG. 4, steps 272and 274 are performed in situ in a furnace or RTP equipment, not in achamber where the dielectric film was formed.

If the dielectric film is tantalum oxide, step 270 forms a tantalumoxide film on a semiconductor substrate to a desired thickness, andsteps 272 and 274 anneal the film in a furnace or RTP equipment. Step272 is performed at between 500 and 700° C., preferably, 600° C., whichis lower than the crystallization temperature of the tantalum oxide.Then, step 274 is performed in situ at between 700 and 900° C.,preferably, 800° C., which is higher than the crystallizationtemperature of the tantalum oxide film. This two-step annealing canremove defects in the tantalum oxide film, e.g., oxygen vacancies andimpurities, and crystallize the dielectric film. Crystallizing of thedielectric film may increase dielectric constant of the dielectric filmbut also increase the leakage current of the dielectric film. This, ifit is not necessary to crystallize the dielectric film, a methoddescribed in FIG. 7 forms an amorphous dielectric film.

Referring to FIG. 7, step 370 deposits a dielectric film on asemiconductor substrate, and step 376 anneals the dielectric film insitu in the same chamber where the dielectric film was formed. Step 376is not composed of a first and second annealing as in the methods ofFIGS. 4 to 6, but a one-step annealing is performed in an environmentcontaining ozone (O₃) and oxygen (O₂) gases at a temperature lower thanthe crystallization temperature of the dielectric film. For example, ifthe dielectric film is tantalum oxide and crystallizing of the tantalumoxide film is not necessary, step 376 anneals the tantalum oxide film atbetween 500 and 700° C., preferably, 600° C., which is lower than thecrystallization temperature of the tantalum oxide. Step 376 is performedin an ozone (O₃) and oxygen (O₂) environment, preferably, the mixingratio of O₃ to O₂ is about 9:1 to produce a similar annealing effect tothe annealing performed at between 700 and 900° C. in an oxygen (O₂)environment.

FIG. 8 illustrates another method for forming and annealing a dielectricfilm according to another embodiment of the present invention. Referringto FIG. 8, forming a dielectric film on a semiconductor substrate (step470), a first annealing (step 472) and a second annealing (step 474) areperformed in-situ in a chamber maintaining an O₂ environment. Step 472is performed at a temperature lower than the crystallization temperatureof the dielectric film. However, step 474 is performed at a temperaturehigher than the crystallization temperature of the dielectric film. Ifthe dielectric film is a tantalum oxide, step 472 is performed at atemperature between 500 and 700° C., preferably about 600° C., and step474 is performed at a temperature between 700 and 900° C., preferablyabout 800° C.

Another aspect of the present invention provides apparatuses illustratedin FIGS. 9 to 11 for forming and annealing a dielectric film in situ.

FIG. 9 is a partial sectional view of a reaction chamber for forming athin film according to an embodiment of the present invention. In FIG.9, a quartz shower head 42 is on the ceiling of a chamber 40, asusceptor 44 for heating a semiconductor substrate 46 to a processingtemperature is on the floor of the chamber 40 below the quartz showerhead 42, and semiconductor substrate 46 is put on the susceptor 44. Apumping line 48 connects to the bottom of the reaction chamber 40 and toan ozone (O₃) decomposer 50. Ozone decomposer 50 connects to a pump 52.A turbo molecular pump (TMP) (not shown), which can change pressurewithin chamber 40, may connect to pump 52. A first gas supply line 56and a second gas supply line 58 respectively connect to quartz showerhead 42. A source gas for forming a thin film is injected into thechamber 40 via the first gas supply line 56. The source gas is a gasfrom a metal oxide group, e.g., the tantalum oxide group, titanium oxidegroup or aluminum oxide group. For example, pentaethoxytantalum(Ta(OC₂H₅)₅) is a source gas for a tantalum oxide. A reaction gas fordepositing the thin film and an annealing gas for annealing the thinfilm are provided to chamber 40 through second gas supply line 58 andshower head 42. When the source gas is for a tantalum oxide thin film,the reaction gas and annealing gas are respectively O₂ and O₃.

Another gas supply line (not shown) may be between shower head 42 and anozonizer 60 connected to second gas supply line 58, so that the reactionand annealing gases are supplied to chamber 40 through respectiveexclusive lines.

An inert gas supply line 58 a, which supplies nitrogen (N₂) gas or argon(Ar) gas for purging of reaction chamber 40 and gas supply lines 56 and58, connects to a part of second gas supply line 58 before ozonizer 60connects to second gas supply line 58. Second gas supply line 58 andinert gas supply line 58 a have first and second mass flow controllers(MFCs) 58 b and 58 c, respectively. An ozone purifying line 54 isbetween the ozonizer 60 and the ozone decomposer 50. One end of theozone purifying line 54 connects to an output end 60 b of the ozonizer60, and the other end of ozone purifying line 54 connects to the ozonedecomposer 50.

Second gas supply line 58 has three valves V1, V2 and V3, ozonepurifying line 54 includes a valve V4, and first gas supply line 56includes a valve V5. The ends of ozonizer 60 are connected to valves V1and V2 of second gas supply line 58, respectively. That is, an input end60 a and output end 60 b of ozonizer 60 respectively connect to valvesV1 and V2.

FIG. 10 is a partial sectional view of a reaction chamber for forming athin film according to another embodiment of the present invention.

Referring to FIG. 10, a second pumping line 48 a is added to theapparatus of FIG. 9 between pumping line 48 and pump 52 so that secondpumping line 48 a bypasses ozone decomposer 50. Chamber 40 directlyconnects to pump 52 via second pumping line 48 a, not through ozonedecomposer 50. Thus, when ozone is not provided to chamber 40 and ozonepurifying line 54, pump 52 can pump chamber 40 efficiently via secondpumping line 48 a, and prevent ozone decomposer 50 from contaminationdue to impurities from gas discharged during deposition of a dielectricfilm. Accordingly, the useful life of the ozone decomposer 50 isprolonged.

When installed, one end of second pumping line 48 a connects to pump 52,and the other end to a valve V6 which controls the direction of gasflowing from chamber 40. That is, valve V6 can make the gas from chamber40 flow into ozone decomposer 50 or along second pumping line 48 a.

To form a composite dielectric film on the semiconductor substrate 46,the supply lines for source gases for the composite dielectric film,e.g., gas supply lines 56 a and 56 b, connect to shower head 42 ofchamber 40. Gas supply lines 56 a and 56 b have valves V6 and V7,respectively. Two or more gas supplying lines may connect to shower head42 according to the type of a composite dielectric film to be formed.

In contrast, in order to make a composite dielectric film, the apparatusof FIG. 10 may have one source gas supply line (not shown) instead ofgas supply lines 56 a and 56 b, and a gas mixer (not shown) may beinstalled upstream of the source gas supply line. The gas mixer mixesmultiple source gases and sends the mixed source gases into chamber 40through the source gas supply line.

Forming and annealing of a dielectric film is described in detail withreference to FIGS. 9 and 12.

In general, before formation of a thin dielectric film, a stabilizationprocess stabilizes previously formed structures, such as transistors, ona semiconductor substrate at a thin film formation temperature, sot hata following thin film formation process does not affect the previouslyformed structures.

Accordingly, after loading the semiconductor substrate 46 on thesusceptor 44 of the reaction chamber 40, the stabilization processanneals semiconductor substrate 46 at a temperature T2 in an N₂environment for a time t1. Typically, temperature T2 is between 400 and600° C., preferably, about 480° C. After the stabilization, a thin filmformation process starts. The thin film is typically a metal oxide filmbelonging to the tantalum oxide group, aluminum oxide group or titaniumoxide group. A tantalum oxide film is preferable. Here, the thin filmmay be formed at between 480 and 500° C. and 0.3 Torr pressure.

In order to form a thin film, a source gas for deposition of the thinfilm, such as pentaethoxytantalum (Ta(OC₂H₅)₅), is supplied to reactionchamber 40 by opening valve V5 of first gas supply line 56 of FIG. 9.Simultaneously, a reaction gas, e.g., O₂ gas, is supplied to reactionchamber 40 by opening valves V1, V2 and V3 of second gas supply line 58.Valves V1 and V2 should be closed to ozonizer 60 to prevent the reactiongas from flowing into ozonizer 60. Semiconductor substrate 46 inreaction chamber 40 is maintained for a time t2 and a predeterminedpressure, e.g., about 0.3 Torr, and a temperature T2 of FIG. 12, so thatthe thin film forms on semiconductor substrate 46. Time t2 depends onthe thickness of the thin film to be formed.

When the thin film formation is complete, valve V1 opens to ozonizer 60so that the oxygen is supplied to ozonizer 60. Here, since valve V2 isstill closed to ozonizer 60, first ozone generated from ozonizer 60 isdischarged to ozone decomposer 50 via ozone purifying line 54. Ozonizer60 starts to generate O₃ before the thin film formation is complete toprovide O₃ to reaction chamber 40 as soon as the thin film formation iscomplete. When the thin film formation is complete, valve V5 closes tostop supplying the source gas, and the ozone from ozonizer 60 remains atoutput end 60 b of ozonizer 60 until the source gases and reactionbyproducts are completely discharged from reaction chamber 40. Duringthis discharge that continues for a time t3, the temperature ofsemiconductor substrate 46 drops from temperature T2 to a temperatureT1. Temperature T1 is between 200 and 700° C., preferably, about 450° C.

After the discharge of the source gases and reaction byproducts, valveV4 closes and valve V2 opens, to supply an O₂ and O₃ gas mixture toreaction chamber 40 for an O₃ annealing of the thin film. Here,preferably, O₂ and O₃ gases are mixed at a ratio of 9:1. The O₃annealing is performed for a time t4 at temperature T1. The annealing onthe thin film is performed at between 200 and 700° C., preferably, about450° C. Here, the pressure in reaction chamber 40 is maintained atapproximately 30 Torr. Time t2 is preferably 2 minutes.

After the O₃ annealing of the thin film, valve V2 opens to chamber 40and closes to ozonizer 60, valve V4 opens, and then N₂ (or O₂) gas issupplied to second gas supply line 58. As a result, the ozone remainingin second gas supply line 58 and chamber 40 is discharged. The ozoneremaining in output end 60 b of ozonizer 60 is discharged outside viaozone purifying line 54 and ozone decomposer 50.

When temperature T2 is different from temperature T1, a lamp heatingmethod is preferred to a resistance heating method to improveproductivity. However, when temperature T2 is similar to temperature T1,and the allowable range of the electrical characteristic valves of thethin film is broad, the resistance heating method is preferred.

When a pressure difference between the thin film formation and theannealing is significant, a Turbo Molecular Pump (TMP) is employed toshorten the time required for shifting between the pressure for formingthe above dielectric film and the pressure for annealing.

Next, dielectric film formation through multiple steps of forming andannealing of the dielectric film is described, with reference to FIGS. 9and 13.

Referring to FIGS. 9 and 13, a stabilization process stabilizessemiconductor substrate 46 by annealing semiconductor substrate 46 attemperature T2′ for a time t1′. Then, a first thin film forms onsemiconductor substrate 46 at temperature T2′ for a time t2′. After thefirst thin film formation is complete, the temperature of semiconductorsubstrate 46 falls from temperature T2′ to temperature T1′ during a timet3′, and a first O₃ annealing at temperature T1′ anneals the first thinfilm for a time t4′. After the first annealing, during a time t5′, theozone in reaction chamber 40 is purified, and the temperature ofsemiconductor substrate 46 is increased from temperature T1′ totemperature T2′. A second thin film which is the same as the first thinfilm is formed on the first thin film for a time t6′. After the secondthin film formation is complete, the temperature of semiconductorsubstrate 46 is lowered from temperature T2′ to temperature T1′ during atime t7′. Then, a second O₃ annealing anneals the second thin film for atime t8′. Then, ozone remaining in reaction chamber 40 is dischargedfrom the reaction chamber.

The operation of the apparatus during depositing and annealing the firstand second thin films is the same as the operation described above withreference to FIGS. 9 and 12. The deposition and annealing of first andsecond thin films are performed in situ in chamber 40.

FIG. 11 is a schematic plan view of a reaction chamber 62 according tostill another embodiment of the present invention. Reaction chamber 62can have the same attachments, such as the gas supply lines, theozonizer, etc., as chamber 40 of FIGS. 9 or 10. However, an internalstructure of chamber 62 differs from that of chamber 40. While chamber40 of FIGS. 9 and 10 can process one semiconductor substrate at a time,chamber 62 of FIG. 11 has multiple semiconductor substrate mountingstands A1, A2, A3, A4 and A5 for simultaneous processing of multiplesemiconductor substrates. Each of semiconductor substrate mountingstands A1, A2, A3, A4 and A5 is equivalent to susceptor 44 of FIGS. 9and 10.

Referring to FIG. 11, semiconductor substrate mounting stand A1stabilizes a semiconductor substrate by a pre-heating, and semiconductorsubstrate mounting stands A2 to A5 deposit and anneal a dielectric filmin situ. The dielectric film includes a metal oxide such as a tantalumoxide (Ta₂O₅), a titanium oxide (TiO₂), an aluminum oxide (Al₂O₃), anyttrium oxide, a vanadium oxide and a niobium oxide.

A fork assembly 64 placed at a center of chamber 62 transports thesemiconductor substrates among semiconductor substrate mounting standsA1 to A5. The semiconductor substrates can simultaneously move in adirection indicated by arrows of FIG. 11.

Shower heads (not shown), which face the respective semiconductorsubstrate mounting stands A2 to A5, are on a ceiling of chamber 62. Eachof the shower heads operates in the same way as the shower heads ofFIGS. 9 and 10. Thus, O₂ or O₃ gas is supplied to each of semiconductorsubstrate mounting stands A1 and A2 via the shower heads. Chamber 62includes a transfer module (not shown) having an aligning stage and acooling stage. When a semiconductor substrate is loaded into chamber 62,the semiconductor substrate is aligned on the aligning stage and thenloaded to semiconductor substrate mounting stand A1. When thesemiconductor substrate is unloaded from reaction chamber 62 after adielectric film deposition and annealing are complete, fork assembly 64transports the semiconductor substrate from one of semiconductorsubstrate mounting stands A2 to A5 to the cooling stage.

Chamber 62 further includes a spray means capable of flowing an inertgas such as nitrogen around each shower head, to form a gas curtainisolating semiconductor substrate mounting stands A1 to A5 from oneanother. For the spray means, each shower head may include an additionalinlet for inert gas that is supplied to gas outlets formed at the edgeof the shower head.

An exemplary operation of chamber 62 in forming and annealing a 100 Åthick dielectric film is described.

A first semiconductor substrate is loaded on semiconductor substratemounting stand A1 from the aligning stage and pre-heated. Then, forkassembly 64 transports the first semiconductor substrate tosemiconductor substrate mounting stand A2, and a second semiconductorsubstrate is loaded on empty semiconductor substrate mounting stand A1.

While the second semiconductor substrate is pre-heated on semiconductorsubstrate mounting stand A1, a tantalum oxide film forms to a thicknessof 25 Å on the first semiconductor substrate on semiconductor substratemounting stand A2. Subsequently, the tantalum oxide film is annealed ata temperature lower than the crystallization temperature of the tantalumoxide film, preferably, about 450° C. Then, fork assembly 64 transportsthe second and first semiconductor substrates respectively fromsemiconductor substrate mounting stands A1 and A2 to semiconductorsubstrate mounting stands A2 and A3, and loads a third semiconductorsubstrate to empty semiconductor substrate mounting stand A1. While thethird semiconductor substrate is pre-heated, a tantalum oxide film formson the second semiconductor substrate to a thickness of 25 Å, and thetantalum oxide film on the first semiconductor substrate becomes 50 Å. Asubsequent annealing anneals the first and second semiconductorsubstrates. Then, fork assembly 64 transports the third, second andfirst semiconductor substrates respectively from semiconductor substratemounting stands A1, A2 and A3 to semiconductor substrate mounting standsA2, A3 and A4, and loads a fourth semiconductor substrate to emptysemiconductor substrate mounting stand A1. While the fourthsemiconductor substrate is pre-heated, a tantalum oxide film forms onthe third semiconductor substrate to a thickness of 25 Å, and thetantalum oxide films on the first and second semiconductor substratesrespectively become 75 Å and 50 Å. A subsequent annealing anneals thefirst, second and third semiconductor substrates. Then, fork assembly 64transports the fourth, third, second and first semiconductor substratesrespectively from semiconductor substrate mounting stands A1, A2, A3 andA4 to semiconductor substrate mounting stands A2, A3, A4 and A5, andloads a fifth semiconductor substrate to empty semiconductor substratemounting stand A1. Again, while the fifth semiconductor substrate ispre-heated, a tantalum oxide film forms on the fourth semiconductorsubstrate to a thickness of 25 Å, and the tantalum oxide films on thefirst, second and third semiconductor substrates respectively become 100Å, 75 Å and 50 Å. A subsequent annealing anneals the first, second,third and fourth semiconductor substrates. Then, fork assembly 64transports the first, second, third, fourth and fifth semiconductorsubstrates respectively from semiconductor substrate mounting stands A5,A4, A3, A2 and A1 to semiconductor substrate mounting stands A1, A5, A4,A3 and A2. Next, fork assembly 64 transports the first semiconductorsubstrate having the 100 Å thick tantalum oxide film from semiconductorsubstrate mounting stand A1 to the cooling stage, and loads a sixthsemiconductor substrate to empty semiconductor substrate mounting standA1. The second to sixth semiconductor substrates subsequently go throughthe same steps as the first semiconductor substrate. As described above,the forming and annealing of the dielectric films can be formed in situon multiple semiconductor substrates.

Reaction chamber 62 can operate in another way where dielectric filmdeposition and annealing are performed on respective exclusivesemiconductor substrate mounting stands. For example, the depositionprocess is performed only on semiconductor substrate mounting stands A2and A4, and the annealing process is performed only on semiconductorsubstrate mounting stands A3 and A5. For this kind of operation, atleast three exclusive semiconductor substrate mounting stands arerequired for pre-heating, dielectric film formation, and dielectric filmannealing, respectively. It is preferable that a reaction chamberincludes the same number of semiconductor substrate mounting standsexclusively for the dielectric film formation as those exclusively forthe dielectric film annealing.

Referring FIG. 11, the operation of chamber 62 having exclusivesemiconductor substrate mounting stands is described.

A semiconductor substrate is loaded from the aligning stage tosemiconductor substrate mounting stand A1, pre-heated, and thentransported to semiconductor substrate mounting stand A2. When theshower head supplies source and reaction gases, a dielectric film formson the semiconductor substrate before the semiconductor substrate istransported to semiconductor substrate mounting stand A3 and annealedusing O₂ or O₃ gas. In order to make the dielectric film thicker, thesemiconductor substrate is transported to semiconductor substratemounting stand A4 for an additional dielectric film formation and tosemiconductor substrate mounting stand A5 for an O₂ or O₃ annealing. Informing the dielectric film on semiconductor substrate mounting stand A2or A4, valves V1′ and V2′ (not shown), equivalent to valves V1 and V2 ofFIG. 9 or 10, operate to supply the source and reaction gases. That is,valves V1′ and V2′ are closed to an ozonizer (not shown) and open toreaction chamber 62. In contrast, the shower heads above substratemounting stand A3 and A5 supply only a gas for annealing the dielectricfilm.

Preferably, in forming a dielectric film using reaction chamber 62, thetime for a each dielectric film formation is almost the same as that foreach dielectric film annealing, and the pressures and temperaturesbetween the dielectric film formation and annealing are so similar toeach other that the formation on one semiconductor substrate mountingstand does not affect the annealing on another semiconductor substratemounting stand, and vice versa.

In addition, reaction chamber 62 can be operated such that foursemiconductor substrates are loaded to semiconductor substrate mountingstands A2 to A5, and dielectric film forming and annealing are performedon each semiconductor substrate. Here, the dielectric film forming andannealing can be performed through multiple steps. Chamber 62 can havemultiple source gas supply lines like chamber 40 of FIG. 10.

Referring to FIGS. 9 and 10, valve V1 can be replaced with three valves:one before valve V1, a second one after valve V2 and a third one atinput end 60 a of ozonizer 60.

Although described with reference to forming a dielectric film,aforementioned embodiments of the present invention can be applied toforming other films including insulating or conductive films.

The in situ formation and annealing of a dielectric film of asemiconductor device according to the present invention reduces thetotal time required to produce the dielectric film, and thus increases aproductivity of a process manufacturing the semiconductor device. Inaddition, the in situ formation and annealing can prevent contaminationof the film with impurities encountered when transporting thesemiconductor device between equipment for dielectric film formation andequipment for dielectric film annealing. The invention integrates areaction chamber for forming a dielectric film and another reactionchamber for annealing the dielectric film into one reaction chamber.

While the present invention has been illustrated and described withreference to specific embodiments, further modifications and alterationswithin the spirit and scope of this invention will occur to thoseskilled in the art.

What is claimed is:
 1. An apparatus for forming a film on a substrate,comprising: a reaction chamber having a first gas inlet and a second,separate gas inlet; a shower head in the reaction chamber; a mountingstand in the reaction chamber, below the shower head, onto which thesubstrate is loaded; a first gas supply connected to the shower headthrough the first gas inlet; a second gas supply connected to the showerhead through the second gas inlet; an ozonizer connected to the secondgas supply; a pumping line; an ozone decomposer connected to thereaction chamber via the pumping line; a pump connected to the ozonedecomposer; and an ozone purifying line between the ozone decomposer andthe ozonizer, wherein the first gas supply supplies to the shower head asource gas for forming the film, and the second gas supply supplies tothe shower head a reaction gas for forming the film and an annealing gasfor annealing the film.
 2. The apparatus of claim 1, wherein the firstgas supply comprises a plurality of gas supply lines, with respectivegas supply lines supplying respective component gases of the source gas.3. The apparatus of claim 1, wherein the reaction gas is oxygen (O₂) andthe annealing gas is ozone (O₃).
 4. The apparatus of claim 1, furthercomprising first, second, and third valves in the second gas supply, afourth valve installed on the ozone purifying line, and a fifth valve inthe first gas supply.
 5. The apparatus of claim 4, wherein an input endand an output end of the ozonizer respectively connect to the first andsecond valves.
 6. The apparatus of claim 5, further comprising an inertgas supply line connected to the second gas supply.
 7. The apparatus ofclaim 5, wherein the ozone purifying line connects to the output end ofthe ozonizer.
 8. The apparatus of claim 1, further comprising aplurality of mounting stands.
 9. The apparatus of claim 8, furthercomprising a plurality of shower heads, each shower head facing acorresponding one of the mounting stands.
 10. The apparatus of claim 9,further comprising a gas spraying means capable of forming an aircurtain of an inert gas around each of the shower heads.
 11. Anapparatus for forming a film on a substrate, comprising: a reactionchamber having a first gas inlet and a second, separate gas inlet; ashower head in the reaction chamber; a mounting stand in the reactionchamber, below the shower head, onto which the substrate is loaded; afirst gas supply connected to the shower head through the first gasinlet; a second gas supply connected to the shower head through thesecond gas inlet; an ozonizer connected to the second gas supply; apumping line; an ozone decomposer connected to the reaction chamber viathe pumping line; and a pump connected to the ozone decomposer, a secondpumping line connected to the pumping line and the pump, the secondpumping line by passing the ozone decomposer, wherein the first gassupply supplies to the shower head a source gas for forming the film,and the second gas supply supplies to the shower head a reaction gas forforming the film and an annealing gas for annealing the film.
 12. Theapparatus of claim 11, further comprising an ozone purifying linebetween the ozone decomposer and the ozonizer.
 13. The apparatus ofclaim 12, further comprising first second, and third valves in thesecond gas supply, a fourth valve installed on the ozone purifying line,and a fifth valve in the first gas supply.
 14. The apparatus of claim13, wherein an input end and an output end of the ozonizer respectivelyconnect to the first and second valves.
 15. The apparatus of claim 14,further comprising an inert gas supply line connected to the second gassupply.
 16. The apparatus of claim 14, wherein the ozone purifying lineconnects to the output end of the ozonizer.
 17. An apparatus for forminga film on a substrate, comprising: a reaction chamber having a first gasinlet and a second, separate gas inlet; a plurality of mounting standsin the reaction chamber onto which the substrate is loaded; a pluralityof shower heads, each shower head facing a corresponding one of themounting stands in the reaction chamber; a first gas supply connected tothe shower heads through the first gas inlet; and a second gas supplyconnected to the shower heads through the second gas inlet, a gasspraying means capable of forming an air curtain of an inert gas aroundeach of the shower heads wherein the first gas supply supplies to theshower heads a source gas for forming the film, and the second gassupply supplies to the shower heads a reaction gas for forming the filmand an annealing gas for annealing the film.
 18. The apparatus of claim17, further comprising an ozonizer connected to the second gas supply.19. The apparatus of claim 18, further comprising: a pumping line; anozone decomposer connected to the reaction chamber via the pumping line;and a pump connected to the ozone decomposer.
 20. The apparatus of claim19, further comprising an ozone purifying line between the ozonedecomposer and the ozonizer.
 21. The apparatus of claim 20, furthercomprising first, second, and third valves in the second gas supply, afourth valve installed on the ozone purifying line, and a fifth valve inthe first gas supply.
 22. The apparatus of claim 21, wherein an inputend and an output end of the ozonizer respectively connect to the firstand second valves.
 23. The apparatus of claim 22, further comprising aninert gas supply line connected to the second gas supply.
 24. Theapparatus of claim 22, wherein the ozone purifying line connects to theoutput end of the ozonizer.
 25. The apparatus of claim 19, furthercomprising a second pumping line connected to the pumping line and thepump, the second pumping line bypassing the ozone decomposer.